Force measuring device



F. KRICKLER FORCE MEASURING DEVICE Aug. 28, 1945.

Filed Feb. 23, 1944 FIG. 1

FIG. 2

INVENTORH FRANK. KRICKLER 2 al/radar I II m m afar/ ATTORNEY I cl! x M I UV m 9 Pat nted Au 28, n I 2,383,554-

um'rso s'rAiasr raur OFFICE FORCE MEASURING DEVICE Frank Krickler, Cleveland, Ohio, assignor :to Curtis-Wright Corporation, a corporation of Delaware I Application February 23, 1944, Serial No. 523,774 10 Claims. .(Cl. 73-133) This invention relates to adorce measuring As illustrated in Figure l, the device includes device which, although not necessarily limited a cylinder 1 which is mounted upon the conto such use, is characterized by features which .trol stick by a bracket 8, The lower section of adapt it particularly. for measuring the forces the'cylinder 1 is adapted to contain a body of which must be applied to the control stick of an 5 hydraulic fluid, the bottom wall 9 being formed airplane tooperate'the control surfaces to which with outlet ports l0 and H which are accessible thesaid stick is connected.= through .an opening l2 in the bracket 8. The

In the design of the control system of an air- I port I0 is provided for drainage purposes, being plane, the calculated values of the aerodynamic closed by a suitable plug. A fitting i3 which forces to which the control surfaces will besub- 10 screws into the port ii, connects one end of a Jected, and. hence theforceswhich will be trans- I tube ll to the lower end of the cylinder I, the mitted to the control stick, may vary in subother end of the said tube being connected to stantial degree from the actual values. It is a suitable pressure-responsive gauge i 5. The the practice, therefore, to check such calculated flatter mat be graduated in any suitable units values by measuring, underactual flight c'ondiand degrees. 1

.tions, the forces which must be applied to the A piston I8. whi h may. asflsh wn, ca ry an... I control stick to efiect such movement of the v nt nal sea rin s. o upi s th yl r control surfaces as may be necessary to movethe e ng located ve h dy of hy aulic fluid latter to, and hold. them in, various positions in the latter and being normally held .in a reagainst the action of the aerodynamic forces tr cted position by said fluidv and by a sprin I which t nd t e t such surfaces t t i 1 I! which seats in a recess in the bottom wall of One object of the invention is to provide a the underside f the piston. nax e y extendsdevice which may be availed of to measure acing neck it on the upper end of the piston it curat'ely and directly the forces which are apcarries a, head i9.- The upper face of the latter plied to the control stick of an airplane under Provides a seat f a n annular dance 20 actual conditions of flight, this object contemformed on a hemispherical element 2| h c is plating a device which is'so designed and which carried by, and at, the lower end of a lever at,

is adapted to be associated with the control t e up r e d of the lever 'car yin -a'hand ip stick in such amanner that, regardless of their 23 which corresponds in Shap and elevation to direction, it will'measure and indicate all forces the ip on he o r l Stick he flange which are applied to th control stick, on the element 2! is held seated on the head it) A further object is a device wherein provision gby a cap-piece 24 which screws onto the threaded is made for compensating for variable factors upper end of t e cy nde the top wall of the which might otherwise impair the accuracy of 3:, s id cap-piece being formed with an p nin 5 the measurements. through which the lever 22 extends and in which A still "further object is to provide a device I the pper unded portion of the e ement 2! which isin the form 01' an attachment and is accommodated for universal movement. whichmay be applied to, and detached from, It will -be noted that the spring I1 and the the control stick of an airplane with facility. 40 hydraulic fluid in the lower section of the cyl- Figure l is a sectional view or a, device ezninder i normally hold the piston it at the upper bodying the features of the invention, the device limit illustrated, in which position the rounded being shown applied as an attachment to 9. upper side of the element 2! engages the annuconventional control stick. lar seat provided by the wall surrounding the Figure 2 is a similar view of a modified form opening 25. The parts are so designed that of device. 1 when they occupy the positions described the The device, indicated at 5, is shown in conpiston I6, neck i8 thereof, head lii'and the center nection with a control stick 6 by which a pilot about which the element 2|. may rock are all may control theelevator and ailerons of an airlocated in axial alignment. plane, it being understood that. .suc h illustra- In order to determine the forces which must tion is intended by way of example only and be applied to the control stick 6 in the operation I that the device may be availed of to equal ad- I of the airplane, the said stick is controlled by: vantage for measuring forces which must be apapplying such forces directly to the lever 22 of plied to levers toeflect the actuation of various the measuring device. In other words all movekinds of lever-controlled members. merits of the control stick are efiected by mathe cylinder and which fitsover a projection on] noted in the lever 22 will be rocked in the direction in which it is urged, as it is manipulated to move the control stick ,6, to thereby cause the flange 20 of the element 2! to effect a movement of the piston is axially in a direction which will apply pressure to the hydraulic fluid in the cylinder i. Such rocking movement of the lever 22 is relative to the control stick 6. The pressure which is produced by the rocking movement of the lever 22 and which is indicated upon the gauge is, is dependent upon the'magnitude f the relative movement of the lever 22 and this in turn is dependent upon the amount of force which must be applied to the latter to effect the desired movement of the control stick ii. In this connection it will be noted that. the universal mounting of the lever 22 in the manner described has the advantage that any force which is applied to it will be accurately measured and indicated upon the gauge l5 regardless of the direction in which such force is applied to the lever. The concavity which is formed in the under side of the element 25, whereby the flange 20 has what is in eiiect a line contact with the head 89 has the advantage that, preventing adhesion between the element 2| and cap-piece if), .it renders the device more sensitive than would be the case if substantial areas of these two elements were in contact with one another in the neutral position of the lever 22.

A modified form of device is illustrated in Figure 2. In this embodiment, the piston 26 which is actuated by the lever 22 of the device is tubular, having a head at its lower end upon which the spring ll acts and a flange 21 at its upper endwhich is engageable with the flange on the element 2 l. The piston 26, therefore, is actuated by the lever 22 in response to the forces which are applied to it in exactly the same manner as the piston iii of the embodiment of the invention first described. The piston 28, however, is movable in a sleeve 28 which is likewise movable in the cylinder 1, springs 29 which act upon the lower end of the sleeve serving to hold the upper endagainst the top wall of the cap-piece 25. In this embodiment the area of the piston head is substantially less than that of the piston l6. Hence the device is more sensitive, it being this connection when the cap-piece 24 is screwedfurther onto the'cy-linder .1 it moves the piston 26 and sleeve 28 as a unit. When it is unscrewedgthe two parts are in this case also moved as a unit, the piston 26 (by the spring l1 and the sleeve 28 by the springs 29.'

From the foregoing it will be apparent that in body embodiments described the cap-piece 2 of thaeylinder i may be adjusted to compensate for any variations. in the volume of the hydraulic fluid. in the cylinder which may occur as a result of leakage, temperature variations or otherwise' In the use of the device, the cap-piece may be initially adjusted so that any desired gauge reading maybe obtained for a zero stick load, In

fluid, a, piston in said cylinder,

trol stick. In such casethe combined control stick and force measuring device would be substituted for the control stick of the plane during the tests. This would have the advantage that it would enable more accurate measurements than could otherwise be obtained without taking into consideration, and compensating tor, the actual weight of the device.

I ,claim as my invention:

1. A device for measuring the force applied to a universally-mounted control member to move the latter to a predetermined position, said device including a, cylinder which is carried by said member and which contains a body of hydraulic a universally mounted lever carried by said cylinder to which said force is applied, said lever being movable relatively to said control member in a direction and to a degree which correspond to the direction and amount of force required to move said control member to said position, means responsive to the relative movement of said lever for actuating said piston to apply pressure to said fluid, and an indicator responsive to such pressure.

2.. A device for measuring the force applied to a universally-mounted control member to move the latter to a predetermined position, said device including a cylinder which is carried by said member and which contains a body of hydraulic fluid, a piston in said cylinder, a universally mounted lever carried by' said cylinder to which said force is applied, means connecting said lever and piston, whereby any pivotal movement of the former effects an axial movement of the latter to apply pressure to said fluid, and an indicator responsive to such pressure.

' member and which contains a the event that the reading 'for such zero" stick load is positive, then such reading must be subtracted from each final reading to obtain theactual stick load.

Although the device is illustrated as an attachment which is applied to a conventional term of control stick it will be understood that the invention also contemplates the incorporation of the device in, and as apermanent part of, a con- 3. A device for measuring the force applied to a universally-mounted control member to move the latter to a predetermined position, said device including a cylinder which is carried by said body of hydraulic fluid, means for applying a predetermined initial pressure to said fluid, a piston in said cylinder, a. universally mounted lever carried by said cylinder and to which said force is applied, means connecting said lever and piston, whereby any pivotal movement of the former effects an axial movement of the latter to apply additional pressure to said fluid, an indicator responsive to. said pressures, and resilient means for restoring said piston to its original position when said lever is released.

a. A device'for measuring the force applied to a control member, to move the latter to a predetermined position, said device including a cylinder which is carried by said member and which contains a body of hydraulic fluid, a piston in said cylinder, a cap-piece on said cylinder, said cap-piece being longitudinally adjustableto apply a, predetermined initial pressure to said fluid, I a pivotally-mounted lever carried by said cylinder and to whichsaid force is applied, means connecting said lever and piston, whereby any pivotal movement of the former effects an axial movement of the latter toapply additional pres sure to said fluid, and an indicator responsive to said pressures. v

5. A device for measuringthe force applied to a control member to move the latter to a predetermined-position, said device including a cylinder which is carried by said member and which contains a body of hydraulic fluid, a piston in said cylinder, said piston having a head, a cappiece on said cylinder, said cap-piece being formed saidcylinder, mounted lever carried by said cylinder, means for which is carried by said member and which conwith an opening, a lever having one endwhich extends throughisaid opening, a hemispherical element carried by said lever and which seats on said head, the wall of said opening cooperating with said element to permit universal movement said lever, whereby any pivotal movement 0! said lever effects an axial movement of said piston to apply pressure to said fluid, and an indicator responsive to said pressure.

6. A device for measuring the force applied to a control member to move the latter to a predetermined position, said device including acylinder which is carried by said member and which contains a body of hydraulic fluid, a piston in said cylinder, said piston having a head, a cap-piece on said cylinder, said cap-piece being formed with an opening and beingadlustable to apply a predetermined initial pressure to said fluid, a lever having one end which extends through said opening, a hemispherical element carried by said lever which seats on said head, the walls of saidopening cooperating with said element to permit universal movement of said lever, whereby any pivotal movement of said lever eifects an axial movement of said piston to apply an additional pressure to said fluid, an indicator responsive to said pressures, and resilient means vfor restoring said piston to its original released.

7. A device for measuring the force applied to a control member to move the latter to a predetermined position, said device including a cylinder which is carried by said member and which contains a body of hydraulic fluid, a sleeve in a piston in said sleeve, a pivotally position when said lever is longitudinally adjusting said sleeve with respect to said fluid, meanslconnecting said lever and piston, whereby any pivotal movement of the former efl'ects an axial movement to apply pressure to said fluid, and responsive to said pressure.

8. A device for measuring the force applied to a control member to move, the latter-to a predetermined pasition, said device including a cylinder an indicator of the latter tains a body of hydraulic fluid, a cap-piece on said cylinder, a sleeve in said cylinder, a piston in said sleeve, 2. pivotally mounted lever can'ied by said cylinder, said cap-piece being adjustable to vary the positions of said sleeve and piston with respect to said fluid, means connecting said lever and piston, whereby any pivotal movement of the former efiects an axial movement of the latter to apply pressure to said fluid, and an indicator responsive to said pressure.

9. A device for measuring the force applied to a control lever mounted for universal movement about a main pivot, comprising a second lever mounted for limited universal movement about a secondary pivot, said secondary pivot being in afixed position with'respect to and moving with said control lever, and the axes of said levers being so alined that a force applied to said second lever will tend to move said control lever in secondary pivot. said secondary pivot being in a flxed position with respect to and moving with said control lever, and the angles between the axes of said levers in the normal or inactive position being substantially zero s'o thata force applied to said second lever will tend to move said control lever in the same direction, means forresisting universal movement of said second lever, and means for measuring the force resisting movement of said second lever about its universal mounting when it reaches a value substantially equal to the force necessary to move said control lever about its universal mounting.- a FRANK KRICKLER. 

